A precast concrete building unit of half-room configuration with a web portion (which may form a ceiling, a floor, or a ceiling of a room on one storey of a multi-storey building and the floor of the storey above it) and opposite half-wall defining flange portions was taught by the inventor in his U.S. Pat. No. 5,081,805, the disclosure of which is herein incorporated by reference. The structure taught in that patent uses matching ridge and depression insert elements placed in a mold forming the bases of the flanges with mating tongue and groove shear keys when the units are connected flange-to-flange as upright/inverted unit pairs to form whole rooms. Staggered blocks mounted on the top edges of the top plates project into the mold to form interlocking bearing surfaces for mating diagonally positioned web-to-web upright/inverted unit pairs. Units formed in the same mold can be used for rooms, columns, shear walls, retaining walls, elevator shafts, stairwells, girders and pedestrian bridges.
In the inventor's U.S. Pat. No. 5,205,943, he teaches that a U-shaped, half-room precast concrete building unit can be molded in an open box-like framework having four L-shaped corner assemblies, facing pairs of horizontal legs of which are respectively joined by laterally-extending telescoping spacers, and facing pairs of vertical legs of which are respectively each joined by two laterally-spaced longitudinally-extending plates. Inserts having alternating voids and blocks are placed longitudinally between the vertical leg pairs to form complementary block and void patterns on the molded unit juncture edges. Retainers having projections are placed over the top edges of the plates to form complementary tongue and groove portions. Relative dimensions of the molded unit are selectable through adjustment of the relative positions of the corner assemblies. The teaching of U.S. Pat. No. 5,205,943 is herein incorporated by reference.
In U.S. Pat. No. 1,516,074 Borg teaches a method of making a monolithic concrete structure in which a plurality of slabs are supported by another plurality of columns. Borg does not teach the use of a wall member having a length essentially coextensive with that of a wall. Moreover, Borg does not teach providing two dimensional support of horizontally extensive portions of his structure while the structure is being grouted together.